Method and apparatus for efficient idle operation in a dual-SIM CDMA 1X mobile station

ABSTRACT

Methods and apparatus are provided for selecting identifying numbers associated with a mobile station (MS) having multiple subscriber identity modules (SIMs) such that the paging intervals for both identifying numbers are aligned. The MS having multiple SIMs may operate in a network via a particular radio access technology (RAT), such as Code Division Multiple Access (CDMA) 1×RTT (1 times Radio Transmission Technology). By having aligned paging intervals, the MS may wake up only once during the paging cycles for the various identifying numbers rather than waking up multiple times, thereby reducing power consumption of the MS during idle mode compared to a conventional MS with multiple SIMs, and thus multiple identifying numbers.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is related to Ser. No. 12/903,034, entitled “Method andApparatus for Efficient Idle Operation in a Dual SIM WCDMA MobileStation,” filed concurrently herewith, which is expressly incorporatedby reference herein in its entirety.

BACKGROUND

1. Field

Certain aspects of the present disclosure generally relate to wirelesscommunications and, more particularly, to selecting identifying numbersassociated with a mobile station (MS) having multiple subscriberidentity modules (SIMs) such that the paging slots for both identifyingnumbers are aligned in an effort to reduce power consumption during anidle mode.

2. Background

Wireless communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources. For example, one network may be a 3G (thethird generation of mobile phone standards and technology) system, whichmay provide network service via any one of various 3G RATs includingEVDO (Evolution-Data Optimized), 1×RTT (1 times Radio TransmissionTechnology, or simply 1×), W-CDMA (Wideband Code Division MultipleAccess), UMTS-TDD (Universal Mobile Telecommunications System—TimeDivision Duplexing), HSPA (High Speed Packet Access), GPRS (GeneralPacket Radio Service), and EDGE (Enhanced Data rates for GlobalEvolution). The 3G network is a wide area cellular telephone networkthat evolved to incorporate high-speed internet access and videotelephony, in addition to voice calls. Furthermore, a 3G network may bemore established and provide larger coverage areas than other networksystems.

A wireless communication network may include a number of base stationsthat can support communication for a number of mobile stations. A mobilestation (MS) may communicate with a base station (BS) via the downlinkand uplink. The downlink (or forward link) refers to the communicationlink from the base station to the mobile station, and the uplink (orreverse link) refers to the communication link from the mobile stationto the base station. A base station may transmit data and controlinformation on the downlink to a mobile station and/or may receive dataand control information on the uplink from the mobile station.

As mentioned above, CDMA 1× is one type of 3G RAT that may be used inproviding network service. One of the CDMA2000 family of mobiletechnology standards, CDMA 1× uses the same RF bandwidth as IS-95: aduplex pair of 1.25 MHz radio channels. CDMA 1× almost doubles thecapacity of IS-95 by adding 64 more traffic channels to the forwardlink, orthogonal to (in quadrature with) the original set of 64. TheCDMA 1× standard enables up to 100 callers to share a single 1.25 MHzCDMA channel and provides a peak data rate of 153 kbps.

SUMMARY

In an aspect of the disclosure, a method for communicating in a radioaccess technology (RAT) network is provided. The method generallyincludes providing a first identifying number associated with a mobilestation (MS), selecting a second identifying number such that a firstpaging interval for the first identifying number is aligned with asecond paging interval for the second identifying number, andassociating the second identifying number with the MS.

In an aspect of the disclosure, an apparatus for communicating in anetwork via a RAT is provided. The apparatus generally includes meansfor providing a first identifying number associated with a MS, means forselecting a second identifying number such that a first paging intervalfor the first identifying number is aligned with a second paginginterval for the second identifying number, and means for associatingthe second identifying number with the MS.

In an aspect of the disclosure, an apparatus for communicating in anetwork via a RAT is provided. The apparatus generally includes at leastone processor and a memory coupled to the at least one processor. The atleast one processor is typically configured to provide a firstidentifying number associated with a MS, to select a second identifyingnumber such that a first paging interval for the first identifyingnumber is aligned with a second paging interval for the secondidentifying number, and to associate the second identifying number withthe MS.

In an aspect of the disclosure, a computer-program product forcommunicating in a network via a RAT is provided. The computer-programproduct generally includes a computer-readable medium having code forproviding a first identifying number associated with a MS, for selectinga second identifying number such that a first paging interval for thefirst identifying number is aligned with a second paging interval forthe second identifying number, and for associating the secondidentifying number with the MS.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and embodiments of the disclosure will become more apparent fromthe detailed description set forth below when taken in conjunction withthe drawings in which like reference characters identify correspondinglythroughout.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication system in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram conceptually illustrating an example of a basestation (BS) in communication with a mobile station (MS) in a wirelesscommunication system in accordance with certain aspects of the presentdisclosure.

FIG. 3 illustrates various intervals in a Code Division Multiple Access(CDMA) 1×RTT (1 times Radio Transmission Technology) paging cycle, inaccordance with certain aspects of the present disclosure.

FIG. 4 illustrates the least significant 10 digits of an InternationalMobile Subscriber Identifier (IMSI), forming a short IMSI (IMSI_S), inaccordance with certain aspects of the present disclosure.

FIG. 5 illustrates the paging intervals for two different IMSIs in asingle mobile station (MS) being offset, in accordance with certainaspects of the present disclosure.

FIG. 6 is a functional block diagram conceptually illustrating exampleblocks executed to select identifying numbers associated with a mobilestation (MS) having multiple subscriber identities such that the pagingintervals for the multiple identifying numbers are aligned, inaccordance with certain aspects of the present disclosure.

FIG. 7 illustrates the paging intervals for two different IMSIs in asingle MS being completely aligned, in accordance with certain aspectsof the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

An Example Wireless Communication System

The methods and apparatus of the present disclosure may be utilized in abroadband wireless communication system. The term “broadband wireless”refers to technology that provides wireless, voice, Internet, and/ordata network access over a given area. The various concepts presentedthroughout this disclosure may be implemented across a broad variety oftelecommunication systems, network architectures, and communicationstandards. By way of example and without limitation, the aspects of thepresent disclosure illustrated in FIG. 1 are presented mainly withreference to a CDMA 1× system.

FIG. 1 illustrates an example of a wireless communication system 100.The wireless communication system 100 may be a broadband wirelesscommunication system. The wireless communication system 100 may providecommunication for a number of cells 102, each of which is serviced by abase station (BS) 104. A base station 104 may be a fixed station thatcommunicates with mobile stations 106. The base station 104 mayalternatively be referred to as a Node B, a base transceiver station(BTS), a radio base station, a radio transceiver, a transceiverfunction, a basic service set (BSS), an extended service set (ESS), anaccess point (AP), or some other suitable terminology.

FIG. 1 depicts various mobile stations 106 dispersed throughout thesystem 100. The mobile stations 106 may be fixed (i.e., stationary) ormobile. A mobile station (MS) 106 may alternatively be referred to bythose skilled in the art as a user terminal, a remote station, asubscriber station, a station (STA), user equipment (UE), a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal (AT), a mobile terminal, awireless terminal, a remote terminal, a handset, a terminal, a useragent, a mobile client, a client, or some other suitable terminology.Examples of a mobile station 106 include a cellular phone, a smartphone, a session initiation protocol (SIP) phone, a laptop, a notebook,a netbook, a smartbook, a wireless modem, a personal digital assistant(PDA), a satellite radio, a global positioning system (GPS) device, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a handheld device, or any othersimilar functioning device.

A variety of algorithms and methods may be used for transmissions in thewireless communication system 100 between the base stations 104 and themobile stations 106. For example, signals may be sent and receivedbetween the base stations 104 and the mobile stations 106 in accordancewith the CDMA 1× techniques. In these cases, the wireless communicationsystem 100 may be referred to as a CDMA 1× system.

A communication link that facilitates transmission from a base station104 to a mobile station 106 may be referred to as a downlink 108, and acommunication link that facilitates transmission from a mobile station106 to a base station 104 may be referred to as an uplink 110.Alternatively, a downlink 108 may be referred to as a forward link or aforward channel, and an uplink 110 may be referred to as a reverse linkor a reverse channel.

A cell 102 may be divided into multiple sectors 112. A sector 112 is aphysical coverage area within a cell 102. Base stations 104 within awireless communication system 100 may utilize antennas that concentratethe flow of power within a particular sector 112 of the cell 102. Suchantennas may be referred to as directional antennas.

FIG. 2 is a block diagram of a BS 104 in communication with a MS 106 ina network 200 operating according to a particular radio accesstechnology (RAT). In the downlink communication, a transmit processor220 may receive data from a data source 212 and control signals from acontroller/processor 240. The transmit processor 220 provides varioussignal processing functions for the data and control signals, as well asreference signals (e.g., pilot signals). For example, the transmitprocessor 220 may provide cyclic redundancy check (CRC) codes for errordetection, coding and interleaving to facilitate forward errorcorrection (FEC), mapping to signal constellations based on variousmodulation schemes (e.g., binary phase-shift keying (BPSK), quadraturephase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadratureamplitude modulation (M-QAM), and the like), spreading with orthogonalvariable spreading factors (OVSF), and multiplying with scrambling codesto produce a series of symbols. Channel estimates from a channelprocessor 244 may be used by a controller/processor 240 to determine thecoding, modulation, spreading, and/or scrambling schemes for thetransmit processor 220. These channel estimates may be derived from areference signal transmitted by the MS 106. The symbols generated by thetransmit processor 220 are provided to a transmit frame processor 230 tocreate a frame structure. The frames are then provided to a transmitter232, which provides various signal conditioning functions includingamplifying, filtering, and modulating the frames onto a carrier fordownlink transmission over the wireless medium through antennas 234. Theantennas 234 may be implemented with beam steering bidirectionaladaptive antenna arrays or other similar beam technologies.

At the MS 106, a receiver 254 receives the downlink transmission throughan antenna 252 and processes the transmission to recover the informationmodulated onto the carrier. The information recovered by the receiver254 is provided to a receive frame processor 260, which parses eachframe, and may provides a portion to a channel processor 294 and thedata, control, and reference signals to a receive processor 270. Thereceive processor 270 then performs the inverse of the processingperformed by the transmit processor 220 in the BS 104. Morespecifically, the receive processor 270 descrambles and despreads thesymbols, and then determines the most likely signal constellation pointstransmitted by the BS 104 based on the modulation scheme. These softdecisions may be based on channel estimates computed by the channelprocessor 294. The soft decisions are then decoded and deinterleaved torecover the data, control, and reference signals. The CRC codes are thenchecked to determine whether the frames were successfully decoded. Thedata carried by the successfully decoded frames will then be provided toa data sink 272, which represents applications running in the MS 106and/or various user interfaces (e.g., display). Control signals carriedby successfully decoded frames will be provided to acontroller/processor 290. When frames are unsuccessfully decoded by thereceiver processor 270, the controller/processor 290 may also use anacknowledgement (ACK) and/or negative acknowledgement (NACK) protocol tosupport retransmission requests for those frames.

In the uplink, data from a data source 278 and control signals from thecontroller/processor 290 are provided to a transmit processor 280. Thedata source 278 may represent applications running in the MS 106 andvarious user interfaces (e.g., keyboard). Similar to the functionalitydescribed in connection with the downlink transmission by the BS 104,the transmit processor 280 provides various signal processing functionsincluding CRC codes, coding and interleaving to facilitate FEC, mappingto signal constellations, spreading with OVSFs, and scrambling toproduce a series of symbols. Channel estimates, derived by the channelprocessor 294 from a reference signal transmitted by the BS 104, may beused to select the appropriate coding, modulation, spreading, and/orscrambling schemes. The symbols produced by the transmit processor 280will be provided to a transmit frame processor 282 to create a framestructure. The frames are then provided to a transmitter 256, whichprovides various signal conditioning functions including amplification,filtering, and modulating the frames onto a carrier for uplinktransmission over the wireless medium through the antenna 252.

The uplink transmission is processed at the BS 104 in a manner similarto that described in connection with the receiver function at the MS106. A receiver 235 receives the uplink transmission through the antenna234 and processes the transmission to recover the information modulatedonto the carrier. The information recovered by the receiver 235 isprovided to a receive frame processor 236, which parses each frame, andprovides a portion to the channel processor 244 and the data, control,and reference signals to a receive processor 238. The receive processor238 performs the inverse of the processing performed by the transmitprocessor 280 in the MS 106. The data and control signals carried by thesuccessfully decoded frames may then be provided to a data sink 239 andthe controller/processor, respectively. If some of the frames wereunsuccessfully decoded by the receive processor, thecontroller/processor 240 may also use an acknowledgement (ACK) and/ornegative acknowledgement (NACK) protocol to support retransmissionrequests for those frames.

The controller/processors 240 and 290 may be used to direct theoperation at the BS 104 and the MS 106, respectively. For example, thecontroller/processors 240 and 290 may provide various functionsincluding timing, peripheral interfaces, voltage regulation, powermanagement, and other control functions. The computer-readable media ofmemories 242 and 292 may store data and software for the BS 104 and theMS 106, respectively. A scheduler/processor 246 at the BS 104 may beused to allocate resources to the MSs and schedule downlink and/oruplink transmissions for the MSs.

An Example Method of Efficient Idle Operation in a Dual-Sim CDMA 1×Mobile Station

In CDMA 1×RTT (or simply CDMA 1×), a MS in idle slotted mode will listento certain recurrent paging intervals. FIG. 3 illustrates variousintervals in a CDMA 1× paging cycle. Within a paging cycle, the paginglistening interval 302 may comprise an 80 ms PCH (Paging Channel)interval 304 preceded by a QPCH (Quick Paging Channel) interval 306 by100 ms. Therefore, the MS may monitor paging messages for a 180 ms timeinterval per paging cycle. The MS may most likely start to monitor PCHat CDMA system time t, in units of 20 ms frame, calculated by:t mod [64*(2^(SLOT) ^(—) ^(CYCLE) ^(—) ^(INDEX)))=4*PGSLOT  (1)The MS may most likely start to monitor the entire paging interval 302(starting at QPCH) at system time t−5 in the above formula.

The above parameter SLOT_CYCLE_INDEX=0, 1, . . . , 7 can determine thelength of a CDMA 1× paging cycle interval 308, namely 1.28 sec*2^(SLOT)^(—) ^(CYCLE) ^(—) ^(INDEX). SLOT_CYCLE_INDEX is typically provisionedat the MS, but a BS may limit the maximum value by broadcasting themaximum of SLOT_CYCLE_INDEX in the System Parameter Message.

Each MS may have a different time offset (PGSLOT) to listen to a CDMApaging message. PGSLOT is a hashed function of the mobile station's IMSI(International Mobile Subscriber Identifier), a unique number associatedwith the MS and used to identify the MS on the network. Typicallycomposed of 15 digits, an IMSI may comprise 3 digits specifying theMobile Country Code (MCC), followed by either 2 (European standard) or 3digits (North American standard) specifying the Mobile Network Code(MNC). The remaining digits may comprise the mobile stationidentification number (MSIN) within the network's customer base.

To calculate the PGSLOT, the least significant 10 digits (34 bits) ofthe IMSI form a short IMSI (IMSI_S) 400 as illustrated in FIG. 4. TheIMSI_S 400 is divided into two fields: IMSI_S2 402 comprising 10 bitsand IMSI_S1 404 comprising 24 bits. For example, one IMSI_S in certaincountries such as the United States has at least 10 digits (e.g.,858-123-4567). In this case, IMSI_S2 comprises the first three digits858, while IMSI_S1 comprises the last seven digits 1234567. As anotherexample from other countries such as China, one IMSI may comprise thedigits 57-12345678. In this case, IMSI_S2 comprises the first threedigits 571, and IMSI_S1 comprises the last seven digits 2345678. Forcertain aspects, the IMSI_S 400 may be a phone number (i.e., a dialingtelephone number) for the MS, while in other aspects, the IMSI_S and thephone number may be dissimilar.

To determine PGSLOT using a hashed function, HASH_KEY is equal to the 32least significant bits of (IMSI_S1+2²⁴×IMSI_S2). L is defined as bits 0to 15 of HASH_KEY, and H is defined as bits 16 to 31 of HASH_KEY.Therefore, PGSLOT is defined as:PGSLOT=└2048×((40503×(L⊕H⊕DECORR))mod 2¹⁶)/2¹⁶┘  (2)where DECORR=6×HASH_KEY [0 . . . 11], ⊕ is the exclusive bit-wiseoperation, └*┘ is the floor function, and HASH_KEY [0 . . . 11] is bits0 to 11 of HASH_KEY.

In some countries, it is popular to operate a mobile station 106 withdual subscriber identity modules (SIMs). With two (or more) SIMs, a usercan make and receive mobile calls with two (or more) different phonenumbers due to the different IMSIs on each SIM. According to equation(2), PGSLOT may have 2048 different possible values: 0, 1, . . . , 2047.

In general, the MS with dual SIMs or IMSIs may monitor paging messagesaccording to different paging intervals 302 because the different IMSIsfrequently lead to different PGSLOT values. Consequently, if the MS hastwo IMSIs (e.g., two phone numbers), the MS may have to monitor forpaging messages twice as long as a MS with only one IMSI (e.g., a singlephone number).

As an example, FIG. 5 illustrates the paging cycle 500 for a first IMSI(IMSI 1) and the paging cycle 502 for a second IMSI (IMSI 2). In FIG. 5,the paging intervals 504 for IMSI 1 are offset a number of PGSLOTs fromthe paging intervals 506 for IMSI 2. Since in idle mode the MS may mostlikely wake up from the idle state during the paging intervals 504, 506to listen for any paging messages, the power consumption of a MS withtwo IMSIs may be approximately double that of a MS with only a singleIMSI during idle mode.

Accordingly, what is needed are techniques and apparatus for reducingthe power consumption during idle mode for a MS with multiple IMSIs.

FIG. 6 is a functional block diagram conceptually illustrating exampleblocks 600 executed to select identifying numbers associated with a MShaving multiple subscriber identities such that the paging intervals forthe multiple identifying numbers are aligned. Operations illustrated bythe blocks 600 may be executed, for example, at the processor(s) 270,280, and/or 290 of the MS 106 from FIG. 2.

The operations may begin, at block 602, by providing a first identifyingnumber (e.g., an IMSI or IMSI_S) associated with the MS. For certainaspects, at least a portion of the identifying number may match a phonenumber for the MS. At block 604, a second identifying number may beselected, such that a first paging interval for the first identifyingnumber is aligned with a second paging interval for the secondidentifying number. For certain aspects, the second identifying numbermay be selected such that the first and second paging intervals may becompletely aligned. Selection of the second identifying number may beperformed, for example, by the MS 106, by the BS 104, or by the network.At block 606, the second identifying number may be associated with theMS.

Following the selection and association of the second identifyingnumber, the MS may enter an idle state outside the aligned first andsecond paging intervals. During the idle state, at least a portion ofthe MS may be powered down in an effort to conserve battery power. Inorder to listen for a paging message, the MS may wake up from the idlestate, powering up at least some of the components of the MS that werepowered down during the idle state. By selecting the second identifyingnumber such that the first and second paging intervals are aligned, theMS may wake up only once during a paging cycle to listen for pagingmessages for both identifying numbers. Consequently, the MS may spendmore time in the idle state, and hence, power consumption may be reducedwhen compared to a conventional dual-SIM MS where the paging intervalsfor the first and second identifying numbers are more likely to beoffset.

As an example of selecting the second identifying number such that thefirst and second paging intervals for the first and second identifyingnumbers are aligned, consider a dual-SIM CDMA 1× mobile phone that canbe allocated with two IMSIs denoted X and Y. If X and Y are properlyselected according to aspects of the present disclosure, then more powermay be conserved in idle mode. The IMSI_S of X and Y may be denoted asX_S and Y_S, respectively. In order to obtain the same paging slot forlistening to paging messages, the IMSI_S portion of the two IMSIs X andY should satisfy:PGSLOT(X _(—) S)=PGSLOT(Y _(—) S)  (3)In equation (3), the PGSLOT (X_S) is the PGSLOT in equation (2) abovewith the IMSI_S equal to X_S, and the PGSLOT (Y_S) is the PGSLOT inequation (2) above with the IMSI_S equal to Y_S.

Typically, the first two or three digits are common for the two IMSI_SsX_S and Y_S. For example, in the United States, this commonality occursbecause the numbers often share the same 3-digit area code, while inother countries, such as China, the first two digits of the IMSI_Sgenerally reflect a common mobile phone service provider. Consequently,with ten digits in the IMSI_S, there may be seven or eight digits thatmay be allocated freely. The hash function of equation (2) may mostlikely randomly distribute these seven- or eight-digit numbers into 2048different values, but only one of the 2048 values will yield the samePGSLOT for both IMSI_Ss X_S and Y_S to meet equation (3). That implies,in turn, that there can be approximately 10⁷/2048≈4900 or10⁸/2048≈49,000 second IMSI numbers available in a dual-SIM MS to meetequation (3) above. If the first digit of the remaining seven or eightdigits of the IMSI_S cannot be zero, then there can be about9·10⁶/2048≈4400 or 9·10⁷/2048≈44,000 second IMSI numbers available in adual-SIM MS to meet equation (3) above. In other words, there areseveral possibilities for selecting Y such that the paging slots for Xand Y (based on X_S and Y_S) are completely aligned.

By selecting a second identifying number in this manner, the pagingintervals 504, 506 for both IMSI 1 and IMSI 2 may be completely alignedas illustrated in FIG. 7. During idle mode, the dual-SIM MS may wake upfrom an idle state to listen for a paging message for either IMSI 1 orIMSI 2 during the aligned paging intervals 504, 506, and the BS 104 maysend a paging message during these intervals. By having only a singlepaging monitoring interval during the paging cycles 500, 502 for IMSI 1and IMSI 2, the power consumption of a dual-SIM MS may be approximatelyequal to that of a single-SIM MS during the idle state (andapproximately half that of a conventional dual-SIM MS with completelynon-aligned paging intervals).

For certain aspects, PGSLOT (X_S) need not exactly equal PGSLOT (Y_S).There may most likely still be a power savings if the two paging slotsfor X_S and Y_S at least overlap. For example, instead of selectingidentifying numbers that meet only one of 2048 values according to thehash function, certain aspects may involve selecting identifying numbersthat meet more than one of the 2048 values (e.g., two of the 2048values), as long as the values are chosen such that the resulting pagingintervals will at least partially overlap to a suitable degree foracceptable power savings. In this manner, a greater number of possibleIMSIs may be selected for at least partially aligning the pagingintervals for the first and second IMSIs.

In one configuration, the apparatus for wireless communication (such asa MS with multiple subscriber identities) includes means for providing afirst identifying number associated with the MS, means for selecting asecond identifying number such that a first paging interval for thefirst identifying number is aligned with a second paging interval forthe second identifying number, and means for associating the secondidentifying number with the MS. For certain aspects, the apparatusfurther comprises means for monitoring for a paging message for eitherthe first or the second identifying number during the aligned first andsecond paging intervals. For certain aspects, the apparatus furthercomprises means for entering an idle state outside the aligned first andsecond paging intervals, wherein the means for monitoring for the pagingmessage is configured to wake up from the idle state. In one aspect, theaforementioned means may be the processor(s) 270, 280, and/or 290configured to perform the functions recited by the aforementioned means.In another aspect, the aforementioned means may be a module or anyapparatus configured to perform the functions recited by theaforementioned means.

Several aspects of a telecommunications system have been presented withreference to a CDMA 1× system. As those skilled in the art will readilyappreciate, various aspects described throughout this disclosure may beextended to other telecommunication systems, network architectures andcommunication standards. By way of example, various aspects may beextended to UMTS (Universal Mobile Telecommunications System) systemssuch as Wideband CDMA (W-CDMA), High Speed Downlink Packet Access(HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed PacketAccess Plus (HSPA+) and Time-Division CDMA (TD-CDMA). Various aspectsmay also be extended to systems employing Long Term Evolution (LTE) (inFDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or bothmodes), Time-Division Synchronized CDMA (TD-SCDMA), Ultra MobileBroadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20,Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. Theactual telecommunication standard, network architecture, and/orcommunication standard employed will depend on the specific applicationand the overall design constraints imposed on the system.

Several processors have been described in connection with variousapparatuses and methods. These processors may be implemented usingelectronic hardware, computer software, or any combination thereof.Whether such processors are implemented as hardware or software willdepend upon the particular application and overall design constraintsimposed on the system. By way of example, a processor, any portion of aprocessor, or any combination of processors presented in this disclosuremay be implemented with a microprocessor, microcontroller, digitalsignal processor (DSP), a field-programmable gate array (FPGA), aprogrammable logic device (PLD), a state machine, gated logic, discretehardware circuits, and other suitable processing components configuredto perform the various functions described throughout this disclosure.The functionality of a processor, any portion of a processor, or anycombination of processors presented in this disclosure may beimplemented with software being executed by a microprocessor,microcontroller, DSP, or other suitable platform.

Software shall be construed broadly to mean instructions, instructionsets, code, code segments, program code, programs, subprograms, softwaremodules, applications, software applications, software packages,routines, subroutines, objects, executables, threads of execution,procedures, functions, etc., whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise. Thesoftware may reside on a computer-readable medium. A computer-readablemedium may include, by way of example, memory such as a magnetic storagedevice (e.g., hard disk, floppy disk, magnetic strip), an optical disk(e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, aflash memory device (e.g., card, stick, key drive), random access memory(RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM(EPROM), electrically erasable PROM (EEPROM), a register, or a removabledisk. Although memory is shown separate from the processors in thevarious aspects presented throughout this disclosure, the memory may beinternal to the processors (e.g., cache or register).

Computer-readable media may be embodied in a computer-program product.By way of example, a computer-program product may include acomputer-readable medium in packaging materials. Those skilled in theart will recognize how best to implement the described functionalitypresented throughout this disclosure depending on the particularapplication and the overall design constraints imposed on the overallsystem.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of exemplary processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, band c. All structural and functional equivalents to the elements of thevarious aspects described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims No claim element is to beconstrued under the provisions of 35 U.S.C. §112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or,in the case of a method claim, the element is recited using the phrase“step for.”

What is claimed is:
 1. A method for selecting identifying numbersassociated with a mobile station communicating in a radio accessTechnology (RAT) network and having multiple subscriber identity modules(SIMs), the method comprising: providing a first identifying numberincluding a first short International Mobile Subscriber Identity(IMSI—S) associated with the mobile station (MS); selecting, via aprocessor, a second identifying number including a second IMSI_S suchthat a first paging interval for the first identifying number isoverlapping with but different from a second paging interval for thesecond identifying number, the first paging interval based at least inpart on a first paging slot that is a function of the first IMSI_S; andassociating the second identifying number with the MS.
 2. The method ofclaim 1, wherein the selecting the second identifying number isperformed by the MS.
 3. The method of claim 1, wherein the function isequal to └2048×((40503×(L⊕H⊕DDECORR))mod 216)/216┘, wherein └L*┘ is afloor function, ⊕ is an exclusive bit-wise operation, IMSI_S1 is thelast seven digits of the first IMSI_S, IMSI_S2 is the first three digitsof the first IMSI_S, HASH_KEY is defined as the 32 least significantbits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY,H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].
 4. The methodof claim 1, wherein the second paging interval is based on a secondpaging slot, the second paging slot is the function of the secondIMSI_S, and the selecting the second identifying number comprisesselecting the second IMSI_S such that the first and second paging slotsare equal.
 5. The method of claim 1, wherein the RAT comprises CodeDivision Multiple Access (CDMA) 1×RTT (one times Radio TransmissionTechnology).
 6. The method of claim 1, further comprising monitoring fora paging message for either the first or the second identifying numberduring the first and second paging intervals.
 7. The method of claim 6,further comprising entering an idle state outside the first and secondpaging intervals, wherein the monitoring for the paging messagecomprises waking up from the idle state.
 8. The method of claim 1,wherein the selecting of the second identifying number comprisesselecting the second identifying number such that the first and secondpaging intervals overlap a predetermined amount to achieve apredetermined power savings.
 9. An apparatus for selecting identifyingnumbers associated with a mobile station communicating in a network viaa radio access technology (RAT) and having multiple subscriber identitymodules (SIMs), the apparatus comprising: means for providing a firstidentifying number including a first short International MobileSubscriber Identity (IMSI_S) associated with the mobile station (MS);means for selecting a second identifying number including a secondIMSI_S such that a first paging interval for the first identifyingnumber is overlapping with but different from a second paging intervalfor the second identifying number, the first paging interval based atleast in part on a first paging slot that is a function of the firstIMSI_S; and means for associating the second identifying number with theMS.
 10. The apparatus of claim 9, wherein the apparatus is the MS. 11.The apparatus of claim 9, wherein the function is equal to^(└)2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘, wherein └L*540 is a floorfunction, ⊕ is an exclusive bit-wise operation, IMSI_S1 is the lastseven digits of the first IMSI_S, IMSI_S2 is the first three digits ofthe first IMSI_S, HASH_KEY is defined as the 32 least significant bitsof (IMSI_S1+224×IMSI_S2), L is defined as bits 0 to 15 of HASH_KEY, H isdefined as bits 16 to 31 of HASH_KEY, HASH_KEY [0 . . . 11] is bits 0 to11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . . 11].
 12. The apparatus ofclaim 9, wherein the second paging interval is based on a second pagingslot, the second paging slot is the function of the second IMSI_S, andthe means for selecting the second identifying number is configured toselect the second IMSI_S such that the first and second paging slots areequal.
 13. The apparatus of claim 9, wherein the RAT comprises CodeDivision Multiple Access (CDMA) 1×RTT (one times Radio TransmissionTechnology).
 14. The apparatus of claim 9, further comprising means formonitoring for a paging message for either the first or the secondidentifying number during the first and second paging intervals.
 15. Theapparatus of claim 14, further comprising means for entering an idlestate outside the first and second paging intervals, wherein the meansfor monitoring for the paging message is configured to wake up from theidle state.
 16. The apparatus of claim 9, wherein the means forselecting the second identifying number is configured to select thesecond identifying number such that the first and second paging overlapa predetermined amount to achieve a predetermined power savings.
 17. Anapparatus for selecting identifying numbers associated with a mobilestation communicating in a network via a radio access technology (RAT)and having multiple subscriber identity modules (SIMs), the apparatuscomprising: at least one processor adapted to: provide a firstidentifying number including a first short International MobileSubscriber Identity (IMSI_S) associated with the mobile station (MS);select a second identifying number including a second IMSI_S such that afirst paging interval for the first identifying number is overlappingwith but different from a second paging interval for the secondidentifying number, the first paging interval based at least in part ona first paging slot that is a function of the first IMSI_S; andassociate the second identifying number with the MS; and a memorycoupled to the at least one processor.
 18. The apparatus of claim 17,wherein the apparatus is the MS.
 19. The apparatus of claim 17, whereinthe function is equal to └2048×((40503×(L⊕H⊕DECORR))mod 216)/216┘,wherein └*┘ is a floor function, ⊕ is an exclusive bit-wise operation,IMSI_S1 is the last seven digits of the first IMSI_S, IMSI S2 is thefirst three digits of the first IMSI_S, HASH_KEY is defined as the 32least significant bits of (IMSI_S1+224×IMSI_S2), L is defined as bits 0to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY, HASH_KEY[0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY [0 . . .11].
 20. The apparatus of claim 17, wherein the second paging intervalis based on a second paging slot, the second paging slot is the functionof the second IMSI_S, and the at least one processor is configured toselect the second identifying number by selecting the second IMSI_S suchthat the first and second paging slots are equal.
 21. The apparatus ofclaim 17, wherein the RAT comprises Code Division Multiple Access (CDMA)1×RTT (one times Radio Transmission Technology).
 22. The apparatus ofclaim 17, wherein the at least one processor is configured to monitorfor a paging message for either the first or the second identifyingnumber during the first and second paging intervals.
 23. The apparatusof claim 22, wherein the at least one processor is configured to enteran idle state outside the first and second paging intervals, wherein theat least one processor is configured to monitor for the paging messageby waking up from the idle state.
 24. The apparatus of claim 17, whereinthe at least one processor is configured to select the secondidentifying number such that the first and second paging intervalsoverlap a predetermined amount to achieve a predetermined power savings.25. A computer-program product for selecting identifying numbersassociated with a mobile station communicating in a network via a radioaccess technology (RAT) and having multiple subscriber identity modules(SIMs), the computer-program product comprising: a non-transitorycomputer-readable medium comprising code for: providing a firstidentifying number including a first International Mobile subscriberIdentity (IMSI_S) associated with the mobile station (MS); selecting asecond identifying number including a second IMSI_S such that a firstpaging interval for the first identifying number is overlapping with butdifferent from a second paging interval for the second identifyingnumber, the first paging interval based at least in part on a firstpaging slot that is a function of the first IMSI_S; and associating thesecond identifying number with the MS.
 26. The computer-program productof claim 25, wherein the selecting the second identifying number isperformed by the MS.
 27. The computer-program product of claim 25,wherein the function is equal to └2048×((40503×(L⊕H⊕DECORR))mod216)/216┘, wherein └*┘ is a floor function, ⊕ is an exclusive bit-wiseoperation, IMSI_S1 is the last seven digits of the first IMSI_S, IMSI_S2is the first three digits of the first IMSI_S, HASH_KEY is defined asthe 32 least significant bits of (IMSI_S1+224×IMSI_S2), L is defined asbits 0 to 15 of HASH_KEY, H is defined as bits 16 to 31 of HASH_KEY,HASH_KEY [0 . . . 11] is bits 0 to 11 of HASH_KEY, and DECORR=6×HASH_KEY[0 . . . 11].
 28. The computer-program product of claim 25, wherein thesecond paging interval is based on a second paging slot, the secondpaging slot is the function of the second IMSI_S, and the selecting thesecond identifying number comprises selecting the second IMSI_S suchthat the first and second paging slots are equal.
 29. Thecomputer-program product of claim 25, wherein the RAT comprises CodeDivision Multiple Access (CDMA) 1×RTT (one times Radio TransmissionTechnology).
 30. The computer-program product of claim 25, wherein thecomputer-readable medium comprises code for monitoring for a pagingmessage for either the first or the second identifying number during thefirst and second paging intervals.
 31. The computer-program product ofclaim 30, wherein the computer-readable medium comprises code forentering an idle state outside the first and second paging intervals,wherein the monitoring for the paging message comprises waking up fromthe idle state.
 32. The computer-program product of claim 25, whereinthe selecting the second identifying number comprises selecting thesecond identifying number such that the first and second paging overlapa predetermined amount to achieve a predetermined power savings.